Abstract
The distribution and morphology of immunoreactive estrogen receptor α (ERα) - containing cells were examined in the cattle brain. The brains were collected from two cows and a male calf. One of the cows was sacrificed one week after parturition. ERα expressions in the preoptic area of the rostral forebrain and the medial basal hypothalamic area were evaluated immunohistochemically using a mouse monoclonal antibody. In all animals, the signals that indicate ERα were detected in the medial preoptic area, the level of the organum vasculosum of the lamina terminalis and the bed nucleus of the stria terminalis. In the caudal hypothalamic region, they were detected in the arcuate nucleus, the periventricular and ventromedial hypothalamic nuclei. ERα-containing cells were characterized by a dense nuclear reaction product. In all the subjects examined, ERα signals were clearly detected in the cytoplasm as well. The density of ERα expression was different among the three cattle; the number of ERα containing cells in the postpartum cow was much lower than that in the other cow and the male calf. The present findings suggest that ERα expression in the forebrain is influenced by the reproductive status in the cattle.
